Exhaust emissions from an internal combustion engine contain pollutants such as hydrocarbons (HC) and carbon monoxide (CO), which are very harmful to the environment. In an attempt to reduce these harmful emissions, strict standards have been established for automobiles using these engines. In geographic areas where air quality is a problem, before obtaining a license for an automobile the automobile must pass an emissions inspection. If the automobile fails the emissions inspection, tuning or repairs must be done to the vehicle until the vehicle is able to pass the inspection requirements, or it cannot be driven in that specific geographical area.
In a typical automobile vehicle inspection, the inspector checks to see whether the vehicle has a fuel inlet restrictor, catalytic converter, and unvented fuel cap. While the car is running, the exhaust emissions are tested for the amount of hydrocarbons and carbon monoxide being released into the environment.
Vehicles are required to be equipped with catalytic converters for limiting the amount of hydrocarbons and carbon monoxide released into the environment. While the use of catalytic converters has been found to be effective in limiting the amount of harmful pollutants released into the environment, such converters tend to be costly and eventually require maintenance or replacement.
Exhaust emission pollutants also need to be limited for off-the-road combustion engines, such as those used in lawn mowers, chain saws, snow blowers and monofilament trimmers. Presently, few or no exhaust emission standards exist for this type of engine. With an increasing need for stricter environmental standards, strict emission requirements limiting the amount of hydrocarbons and carbon monoxide released into the air by these engines will also exist in the future.
For off-the-road engines, it is not economically feasible to locate a catalytic converter or similar device on the exhaust stream outlet of these engines. Such a device would be very costly relative to the overall cost of the off-the-road engine itself. Additionally, a catalytic converter may limit the power required for operation of the engine.
The present invention solves these problems of the prior art by providing a simple and economical way to improve engine exhaust and meet environmental air quality restrictions.